Safari Technology Preview gives developers a look at the upcoming web technologies for OS X and iOS. It is similar to Google Chrome’s Canary builds, however, Apple does not give any sneak peak at new features. At the moment, Safari’s Preview ranks better in benchmarks when compared to Chrome’s developer builds.
The Preview is only compatible with OS X 10.11 El Capitan. It can be downloaded by both developers and non-developers and works along with the stable version of Safari so you can use both side-by-side. Unlike Webkit nightlies, Safari Technology Preview ships with iCloud integration so you sync view your reading list, favorites and synced tabs across all Apple devices.